A long standing problem in electronic circuit design is to supply a predetermined value of average direct current to a load without wasting excessive amounts of electrical energy in a series resistor. Particularly, it is important to supply a gate turn off thyristor with a predetermined current during the conduction phase of the GTO. Previous solutions to supplying a GTO with a control current during conduction have required dissipation of undue amounts of electrical energy in a series resistor. Switching regulators of the prior art have been either excessively complicated or otherwise unsuitable for incorporation in commercial electronic products. Examples of complex switching regulators include U.S. Pat. No. 3,383,584, issued to Atherton on May 14, 1968, and U.S. Pat. No. 4,160,945, issued to Schorr on July 10, 1979. Other switching regulators have been devised for voltage control but are unsuitable for control of current flow into a device requiring a predetermined input current, and representative of these devices is U.S. Pat. No. 3,417,321, issued to Clapp on Dec. 17, 1968.